Ropivacaine

Ropivacaine In Dogs & Cats: Uses, Dosage and Side Effects

Overview

• Reversible blockade of the sodium channel in nerve fibres produces local anaesthesia.

Uses of Ropivacaine

• Provision of analgesia by perineural nerve blocks, regional and epidural techniques.

Dose of Ropivacaine in Dogs and Cats

Dogs:

Perineural:

• The volume of injection depends on the site of placement and size of the animal.
• As a guide: 0.1 ml/kg per injection site for femoral and sciatic nerve blocks; 0.1 ml/kg for each of the three injection sites for the combined radial, ulnar, musculocutaneous and median nerve blocks; 0.3 ml/kg for brachial plexus nerve block; 0.25–1 ml total volume for blockade of the infraorbital, mental, maxillary and mandibular
  nerves.
• Choose an appropriate concentration of ropivacaine to achieve a 2–3 mg/kg dose within these volume guidelines.

Epidural:

• 1–2 mg/kg ropivacaine combined with preservative-free morphine 0.1–0.2 mg/kg.
• Limit the total volume of solution injected into the epidural space to 1 ml/4.5 kg up to a maximum volume of 6 ml to limit the cranial distribution of drugs in the epidural space and prevent adverse pressure effects.

Interpleural:

• mg/kg diluted with normal saline to a total volume of 5–20 ml depending on the size of the animal.
• The solution can be instilled via a thoracotomy tube.
• Dilution reduces pain on injection due to the acidity of ropivacaine.

Cats:

• Do not exceed 2 mg/kg total dose; accurate dosing in cats is essential to prevent overdose.

Side Effects of Ropivacaine in Dogs and Cats

• Inadvertent intravascular injection may precipitate cardiac arrhythmias that are refractory to treatment.

Contraindications of Ropivacaine in Dogs and Cats

• Do not give i.v. or use for i.v. regional anaesthesia.

Some Notes:

• Duration of Action: It offers a relatively long-lasting pain relief effect, lasting between 3 to 8 hours.
• Cardiotoxicity: Ropivacaine is considered safer for the heart compared to bupivacaine, making it a preferred choice to reduce cardiac risks.
• Sensory Nerve Selectivity: It selectively affects sensory nerves more than motor nerves, minimizing motor function blockage after administration.
• Lower Doses for High Absorption: In situations where systemic absorption is likely to be high, like intrapleural analgesia, lower doses of ropivacaine are recommended.
• Dilution for Wider Distribution: Small amounts of ropivacaine can be mixed with normal saline to ensure a broader distribution of the drug for perineural blockade.
• Safe Dosing in Dogs: Dogs can typically tolerate doses of up to 4 mg/kg every 8 hours without significant systemic side effects when administered perineurally, epidurally, or intrapleurally.
• Cautious Dosing in Cats: The safe dose of ropivacaine has not been established for cats, so it is advisable not to exceed a dose of 2 mg/kg in feline patients.
• All local anaesthetics share similar side effects, therefore, the dose of ropivacaine should be reduced when used in combination with other local anaesthetics.
• The addition of adrenaline does not appear to alter the duration of the block.